Clean rooms are enclosed spaces that were first developed in the 1960s as a way to accommodate the sensitive applications of the emerging microtechnology and aerospace industries, which required pristine environments, free of airborne contaminants like moisture and dust. Today, clean rooms continue to facilitate sensitive operations for the aforementioned industries and others, like biotechnology, software engineering, and medical research. They do so by restricting and controlling moisture, dust, and other variables like air temperature and pressure, airborne dust and moisture, chemical vapors, low-level pollutants, and atmospheric conditions.
Clean rooms are rated on a scale of anticipated contaminant control. Manufacturers may choose to measure and classify them using one of four styles, which are US FED STD 209E, ISO 14644-1, BS 5295 and EMP EU. Using US FED STD 209E standards, they are arranged in class numbers that correspond with the number of .5-plus micrometer-sized particles per cubic foot of air contained in the room. Larger numbers are assigned to clean rooms with a higher number of particles allowed in the air. Manufacturers select clean rooms based on application requirements accordingly. For example, for a process that could cause a chemical reaction or wear on the environment around it, a manufacturer should select a Class 100 clean room, which is made of materials that won’t release fibrous contaminants. For a less sensitive application, such as one that will not break down soft materials like plastics or flexible acrylics, a Class 10,000 clean room, which features soft walls and less strict controls, is an appropriate choice. Particles are measured with the help of a discrete particle counting device. Read More…
Using International Organization for Standardization (ISO) standards, clean rooms are arranged on a scale from three to eight, with three being the most effective. For reference and comparison, an ISO Class 5 clean room, which permits up to 100,000 particles per cubic meter, is the equivalent of a Class 100 US FED clean room. Some industries do also use EMP EU standards, which are the standard in the European Union and BS 5295 standards, which are the British standard and measure contaminants in cubic meters. However, most often in the USA, we simply speak in terms of US FED standards.
Clean rooms may be permanently established, or they may have a portable or modular design. Permanent clean rooms and the machines that regulate their conditions are usually incorporated into the structures of the buildings that house them. Sometimes, though, they are enclosed by clear plastic walls or glass instead. The design also varies by size and material. They may be warehouse-sized, as they often are for microelectronics, circuitry, and pharmaceutical product manufacturers; these are called ballrooms. Alternatively, when built for small-scale medical testing, repairs, or limited, exclusive, or specialized operations, they may be only the size of home kitchen ovens. Selected materials have to meet the strict criteria so that the clean room can be effective. Namely, they cannot contribute to air contamination. For example, clean room construction materials must be non-fibrous, non-static electricity-generating and non-corrosive. Even stainless steel is sometimes avoided, because it can corrode when exposed to bleach.
Clean rooms are essential to applications that rely on pristine air quality and particle elimination. These applications include pharmacological studies, infectious disease testing, and various medical research operations and testing procedures. For this reason, clean rooms generally come with an air quality control system of some type, like air filters, fans, and pumps. In fact, the best kept clean rooms have air flow that is controlled by directional air filters that encourage a laminar air flow; using laminar air flow ensures that new, filtered air continuously cycles into the clean room and removes any lingering contaminants. Note that, to keep from tracking in particles, operators and other personnel must don proper clean room apparel; humans shed 100,000 particles of dead skin cells per minute just while standing! Apparel to cover up human skin and hair, which is around 100 micrometers wide, includes shoe covers, beard covers, bouffant caps and face masks, as well as accessories like approved cleaning wipes. In addition, these efforts may be amplified by the use of air showers, which are small rooms in which personnel step to rinse off prior to entering a clean room.